/**
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional information regarding
 * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License. You may obtain a
 * copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package edu.uci.ics.crawler4j.parser;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;

import org.apache.log4j.Logger;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.parser.ParseContext;
import org.apache.tika.parser.html.HtmlParser;

import edu.uci.ics.crawler4j.crawler.Configurable;
import edu.uci.ics.crawler4j.crawler.CrawlConfig;
import edu.uci.ics.crawler4j.crawler.Page;
import edu.uci.ics.crawler4j.url.URLCanonicalizer;
import edu.uci.ics.crawler4j.url.WebURL;
import edu.uci.ics.crawler4j.util.Util;

/**
 * @author Yasser Ganjisaffar <lastname at gmail dot com>
 */
public class Parser extends Configurable
{
    protected static final Logger logger = Logger.getLogger(Parser.class);

    private final HtmlParser htmlParser;
    private final ParseContext parseContext;

    public Parser(CrawlConfig config)
    {
        super(config);
        htmlParser = new HtmlParser();
        parseContext = new ParseContext();
    }

    public boolean parse(Page page, String contextURL)
    {
        String contextURLToParse = contextURL;
        if (Util.hasBinaryContent(page.getContentType())) {
            if (!config.isIncludeBinaryContentInCrawling()) {
                return false;
            } else {
                BinaryParseData parseData = new BinaryParseData();
                parseData.parseData(page.getContentData());
                page.setParseData(parseData);
                return true;
            }
        } else if (Util.hasPlainTextContent(page.getContentType())) {
            try {
                TextParseData parseData = new TextParseData();
                parseData.setTextContent(new String(page.getContentData(), page.getContentCharset()));
                page.setParseData(parseData);
                return true;
            } catch (Exception e) {
                logger.error("Exception when parsing text content of " + contextURL, e);
            }
            return false;
        }

        Metadata metadata = new Metadata();
        HtmlContentHandler contentHandler = new HtmlContentHandler();
        InputStream inputStream = null;
        try {
            inputStream = new ByteArrayInputStream(page.getContentData());
            htmlParser.parse(inputStream, contentHandler, metadata, parseContext);
        } catch (Exception e) {
            logger.error("Exception when parsing metadata of " + contextURL, e);
        } finally {
            try {
                if (inputStream != null) {
                    inputStream.close();
                }
            } catch (IOException e) {
                logger.error("Exception when finally closing input stream of " + contextURL, e);
            }
        }

        if (page.getContentCharset() == null) {
            page.setContentCharset(metadata.get("Content-Encoding"));
        }

        HtmlParseData parseData = new HtmlParseData();
        parseData.setText(contentHandler.getBodyText().trim());
        parseData.setTitle(metadata.get(Metadata.TITLE));
        parseData.setMeta(contentHandler.getMetaTags());

        List<WebURL> outgoingUrls = new ArrayList<WebURL>();

        String baseURL = contentHandler.getBaseUrl();
        if (baseURL != null) {
            contextURLToParse = baseURL;
        }

        int urlCount = 0;
        for (ExtractedUrlAnchorPair urlAnchorPair : contentHandler.getOutgoingUrls()) {
            String href = urlAnchorPair.getHref();
            href = href.trim();
            if (href.length() == 0) {
                continue;
            }
            String hrefWithoutProtocol = href.toLowerCase();
            if (href.startsWith("http://")) {
                hrefWithoutProtocol = href.substring(7);
            }
            if (href.startsWith("https://")) {
                hrefWithoutProtocol = href.substring(8);
            }

            if (!hrefWithoutProtocol.contains("javascript:") && !hrefWithoutProtocol.contains("@")) {
                String url = URLCanonicalizer.getCanonicalURL(href, contextURLToParse);
                if (url != null) {
                    WebURL webURL = new WebURL();
                    webURL.setURL(url);
                    webURL.setAnchor(urlAnchorPair.getAnchor());
                    outgoingUrls.add(webURL);
                    urlCount++;
                    if (urlCount > config.getMaxOutgoingLinksToFollow()) {
                        break;
                    }
                }
            }
        }

        parseData.setOutgoingUrls(outgoingUrls);

        try {
            if (page.getContentCharset() == null) {
                parseData.setHtml(new String(page.getContentData()));
            } else {
                parseData.setHtml(new String(page.getContentData(), page.getContentCharset()));
            }
        } catch (UnsupportedEncodingException e) {
            logger.error("Unknown encoding while parsing " + contextURL, e);

            return false;
        }

        page.setParseData(parseData);
        return true;

    }

}
